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How Much Bigger Can Apple Get?

Apple shares could have funded some of the most expensive endeavors in human history. Is that fair?

Apple(Nasdaq: AAPL) started out 2011 in style by hitting a nice, arbitrary milestone: The company's market cap now stands above the $300 billion mark.

To put that figure into some kind of perspective, you have to resort to ridiculous exercises. If you could liquidate Apple today at full market value (and not counting the $25.6 billion of cash equivalents on Apple's balance sheet), you could:

Fund both the Apollo space program ($120 billion in inflation-adjusted dollars) and the International Space Station (estimates top out at $160 billion). You'd even have $20 billion left over to build a couple of large hadron colliders.

Install fiber broadband to 93% of Australian homes and businesses -- about five times over. Or, make a rather large dent in the woefully lacking broadband infrastructure of the United States, perhaps by buying into the audacious fiber networking plansGoogle is brewing.

Buy a 32-gigabyte iPad with WiFi and 3G connectivity for every man, woman, and child in North America. Talk about a virtuous circle!

Apple would need another 25% boost to pass ExxonMobil(NYSE: XOM) and become the largest company in the world as measured by market cap. Apple generated $14 billion of net income over the past four quarters, which is about half of Exxon's total.

I'm not saying that Apple needs to be worth less than half of what Exxon is fetching -- after all, Apple is still a growth stock and Exxon is not. But I am questioning whether Cupertino can support this nosebleed valuation for much longer using its current playbook. Sure, the iPhone and iPad are nice, but not very different from scaled-up iPods with some extra features. At some point, the addressable market will be saturated and Apple's stock will drop back to earth.